Lawn trimmer or edger



April 11, 1950 A. E. MILLER LAWN TRIMMER 0R EDGER Filed Dec. 4, 1946 v vamen/bot flrthurECfliller,

dwozney Patented Apr. 11, 1950 UNITED STATES PATENT OFFICE LAWN TRIMMEROR EDGER Arthur E. Miller, Milwaukee, Wis.

Application December 4, 1946, Serial No. 714,035

3 Claims.

particularly pointed out in the appended claims.

Briefly, the machine comprises an oscillatory serrated shear blade whichis movable back and forth in resiliently tensioned shearing engagementwith a relatively fixed serrated shear blade, the oscillations of themovable blade being secured through motion translating mechanismoperable by a ground engaging wheel which supports the device for travelover the lawn. The shear blades are disposed substantially parallel toand closely adjacent the ground, whereby spears or tufts of grassgrowing in sidewalk or coping joints or cracks may be cut substantiallyflush with the surface; and the blades are carried by a resilientlybiased frame which is pivotally mounted on the wheel axle for floatingmovements, whereby to accommodate unevenness of the ground surface andprotect the shear blades against being inadvertently driven into theground, with possible consequent damage.

In the accompanying drawing forming a part of this specification thereis shown one form of lawn trimmer embodying the principles of theinvention, it being understood however that this illustration is forpurposes of disclosure only and that the details of construction andprecise arrangement of parts may be varied within the scope of theclaims, without departing from the spirit of the invention.

In the said drawing:

Figure 1 is a side elevational view of the trimmer;

Fig. 2 is a front elevational view thereof, as seen from the right ofFig. 1; and

Fig. 3 is a top plan view, partly broken away and in section.

'Referring to the drawing more in detail, the machine as here showncomprises a single supporting wheel II the hub l2 of which is journalledon an axle l3 which is carried by the companion offset strap members Mand IE to the upper portions of which is secured a tongue or handle I 6whereby the machine may be traversed over the ground. The rim ll of thewheel H has a circumferential groove iii in its periphery, in whichgroove is seated a resilient tire l9; and to each side face of the rimportion ll there is secured an annulus 26 carrying a circumferentialseries of laterally projecting lugs or cams 21. The cams of therespective annuli are circumferentially staggered relative to oneanother, as will be readily understood from Fig. 1. a

A pair of laterally spaced forwardly extending arms have their rearwardend portions journalled on the axle 13 while their forward ends arewelded or otherwise rigidly secured to a vertically disposed sleeve 28in which is slidably mounted a spindle 21. A fixed shear member 23 hasits rearward portion 29 rigidly secured to the said sleeve, and isoffset downwardly as at 30 to bring the heel portion 3! of the shearblade proper to substantially ground level. The forward or toe portion32 of this blade is slightly offset upwardly, as at 33-, and is providedwith V-shaped notches or serrations as to provide a plurality of cuttingteeth 35.

A movable shear member 36 is superposed on the fixed shear member 28 andhas its rearward portion 31 rigidly attached to a sleeve 38 which isjournalled on the spindle 27 above the sleeve 26. The movable shearmember has an inclined portion 39 extending forwardly and downwardlyfrom said rearward portion 31, and the movable shear blade 40 extendsforwardly from the lower end of the inclined portion 39. The bladeportion 40 is notched or serrated as at 4| to provide cutting teeth 42complementing the teeth of the fixed shear blade. A coiled compressionspring 43, interposed between the head 44 of the spindle 21 and thelower end of the sleeve 26, constantly urges the said spindle downwardlyand maintains tensioned shearing engagement between the shearingportions 32 and 59 of the respective blade members. The movable shearmember is preferably so formed that its toothed shearing portion isslightly out of parallel with the companion portion 32 of the fixedshear member, as shown in Fig. 1, whereby in conjunction with the spring43- efiective shearing action throughout the length of the cutting edgesof the teeth 35 and 52 may be obtained at all times. The force exertedby the spring 43 may be varied as conditions require, through adjustmentof a nut threaded on the upper end of the spindie 21.

The sleeve 38 of the movable shear member carries a pair of curved arms46 providing a fork which straddles the rim portion of the wheel ll,

and the free ends of these arms carry rollers 41- disposed forengagement alternately by the staggered cams 2| carried by the wheel.Thus, as the machine is traversed over the ground, rotation of the wheelWill oscillate the fork and move the shear blade 40 back and forthrelative to the blade 32.

A torsion spring 48, the ends of which are engaged with the strap memberl4 and the adjacent pivoted arm'25 respectively, provides a yieldableconnection between the handle it and the floating shear frame, and tendsto maintain engagement between said arm and a lateral projection or toe49 carried by an extension 58 of the said strap member.

By reason of their disposition in proximity to the ground, the shearblades-may cut the grass substantially flush with the ground surface,which is of material advantage in clipping tufts growing in cracks orjoints in copings, walk pavements, etc. However, because the shearblades ,are so closely adjacent the ground, if they were carried byintegral extensions of the handle straps I4 and 5, or were otherwiserigidly mounted relative to the handle l6, as in prior machines of thischaracter, should the handle be inadvertent- 1y elevated beyond thenormal operating inclination shown in Fig. 1, or should the operatorexert abnormal downward pressure on the machine in anefiort to securebetter traction for the cutting of tough or unusual material, the shearmembers would be depressed and caused to penetrate the ground, withprobable consequent damage. This possibility is obviated in the presentconstruction, since the shear-blades are carried by the floating framecomprising the pivoted arms 25 and sleeve 25, which will yield in eitherof the above mentioned contingencies and prevent the shear points frombeing forced into the ground.

Furthermore, with the handle H5 at its normal inclination, should theheel 3| of the fixed blade member encounter a slight elevation orunevenness in the ground surface, the floating shear frame and bladeswill pivot upwardly against the action of spring 48, as indicated inbroken lines in Fig. 1, and thus readily pass over the obstruction.Should an obstruction be encountered which can not be thus cleared, orshould it be desired to increase the height of the cut, the inclinationof the handle l5 may be merely lessened somewhat, whereupon the lu 49 ofthe strap member 14 will elevate the shear frame and blades to thenecessary or desired degree.

What is claimed is:

1. A lawn trimmer, comprising a ground engaging wheel; an axle mountingsaid wheel; handle means for traversing the machine over the ground,mounted on said axle for vertical swinging movements; a shear framemounted on the axle for vertical oscillation independently of saidhandle means; a fixed shear blade carried by said frame adjacent theground-in advance of said wheel, said blade having "an offset heelportion for engagement with the ground; a second shear bladeinountedonsaid frame for oscillatory movements in co-operative relation to saidfirst blade; resilient means urging said frame and blades toward theirlowered position; means carried by said handle means for engagement withsaid frame upon abnormal depression of the handle means, whereby theframe and blades may be elevated; and motion translating means operableby said wheel to oscillate-said second'blade.

2. In an edge trimmer for lawns, the combination of a ground engagingwheel provided with a plurality of arcuately spaced cams; an axlejournalling said wheel; a traversing handle mounted on the axle andswingable about the axis thereof; a shear frame oscillatably mounted bythe axle and extendin forwardly of the wheel; a vertical spindle carriedby the forward portion of said shear frame; a fork structure journalledon said spindle for horizontal movements and having means engageablewith said wheel cams whereby rotation of the wheel may oscillate thefork; a narrow, toothed shear blade fixedly secured to and extendingforwardly from said frame in longitudinal alinement with said wheel andin proximity to the ground; a ground-engaging heel carried by therearward portion of said blade for preventing contact of the forwardportion of the blade with the ground surface; a second narrow, toothedshear blade vertically movably superposed on said fixed blade inslightly non-parallel relation thereto and oscillatable thereover bysaid fork structure; and a'single spring means exerting force solelyupon a longitudinal axial portion of said second blade to maintainyieldable tensioned shearing engagement between the blades irrespectiveof theposition'of the shear frame and handle.

3. In an edge trimmer for lawns, the combination of a ground engagingwheel provided witha plurality of arcuately spaced cams; an axlejournalling said wheel; a traversing handle mounted on the axle andswingable about the axis thereof; a shear frame oscillatably mounted bythe axle and extending forwardly of the Wheel; interengageable stopmeans on the handle and shear frame for limiting relative movementbetween them in one direction; spring means connecting the handle andframe and yieldably maintaining engagement of said stop means wherebythe handle and frame normally move as a unit; a vertical spindle carriedby the forward portion of the shear frame; a fork structure journalledon said spindle for horizontal movements and having .8 means engageablewith said wheel cams whereby rotation of the wheel may oscillate thefork; a toothed shear blade fixedly secured to and extending forwardlyfrom said frame in proximity to the ground; a ground engaging heeladjacent the rearward portion of said blade for preventing contact ofthe forward portion of the blade with the ground surface; a secondtoothed shear blade vertically movably superposed on said fixed blade inslightly non-parallel relation thereto and oscillatable thereover bysaid fork structure; and spring means acting upon said second blade tomaintain yieldable tensioned shearing engagement between the blades.

ARTHUR E. MILLER.

REFERENCES CITED The following references'are of recordin=the file ofthis patent:

UNITED STATES PATENTS Number Name Date 863,960 Wilde Feb. 16,1869 89,981Garrick 'May '11, 1869 421,430 Phillips Feb. 18,1890 700,173 ClifftonMay 20, 1902 2,155,183 Dursch Apr. 18,1939

